Effect of initial particle deposition rate on cake formation during dead-end microfiltration

Advancements in membrane technology for efficient POME treatment: A comprehensive review and future perspectives

The treatment of POME related contamination is complicated due to its high organic contents and complex composition. Membrane technology is a prominent method for removing POME contaminants on account of its efficiency in removing suspended particles, organic substances, and contaminants from wastewater, leading to the production of high-quality treated effluent. It is crucial to achieve efficient POME treatment with minimum fouling through membrane advancement to ensure the sustainability for large-scale applications. This article comprehensively analyses the latest advancements in membrane technology for the treatment of POME. A wide range of membrane types including forward osmosis, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactor, photocatalytic membrane reactor, and their combinations is discussed in terms of the innovative design, treatment efficiencies and antifouling properties. The strategies for antifouling membranes such as self-healing and self-cleaning membranes are discussed. In addition to discussing the obstacles that impede the broad implementation of novel membrane technologies in POME treatment, the article concludes by delineating potential avenues for future research and policy considerations. The understanding and insights are expected to enhance the application of membrane-based methods in order to treat POME more efficiently; this will be instrumental in the reduction of environmental pollution.

Three-Dimensional Reconstruction-Characterization of Polymeric Membranes: A Review

Polymeric membranes serve as vital separation materials in diverse energy and environmental applications. A comprehensive understanding of three-dimensional (3D) structures of membranes is critical to performance evaluation and future design. Such quantitative 3D structural information is beyond the limit of most employed conventional two-dimentional characterization techniques such as scanning electron microscopy. In this review, we summarize eight types of 3D reconstruction-characterization techniques for membrane materials. Originated from life and materials science, these techniques have been optimized to reveal the 3D structures of membrane materials in the separation field. We systematically introduce the theories of each technique, summarize the sample preparation procedures developed for membrane materials, and demonstrate step-by-step data processing, including 3D model reconstruction and subsequent characterization. Representative case studies are introduced to show the progress of this field and how technical challenges have been overcome over the years. In the end, we share our perspectives and believe that this review can serve as a useful reference for 3D reconstruction-characterization techniques developed for membrane materials.

Unveiling the spatiotemporal dynamics of membrane fouling: A focused review on dynamic fouling characterization techniques and future perspectives

Membrane technology has emerged as a crucial method for obtaining clean water from unconventional sources in the face of water scarcity. It finds wide applications in wastewater treatment, advanced treatment, and desalination of seawater and brackish water. However, membrane fouling poses a huge challenge that limits the development of membrane-based water treatment technologies. Characterizing the dynamics of membrane fouling is crucial for understanding its development, mechanisms, and effective mitigation. Instrumental techniques that enable in situ or real-time characterization of the dynamics of membrane fouling provide insights into the temporal and spatial evolution of fouling, which play a crucial role in understanding the fouling mechanism and the formulation of membrane control strategies. This review consolidates existing knowledge about the principal advanced instrumental analysis technologies employed to characterize the dynamics of membrane fouling, in terms of membrane structure, morphology, and intermolecular forces. Working principles, applications, and limitations of each technique are discussed, enabling researchers to select appropriate methods for their specific studies. Furthermore, prospects for the future development of dynamic characterization techniques for membrane fouling are discussed, underscoring the need for continued research and innovation in this field to overcome the challenges posed by membrane fouling.

Monte Carlo simulation of dead-end diafiltration of bidispersed particle suspensions

A two-dimensional Monte Carlo simulation of dead-end diafiltration of bidispersed particle suspensions was performed. The diafiltration process involves separation of components based on their size by using a permeable membrane. The continuous model was applied to study separation of mixture of disks with diameter d and D (D>d). It was assumed that the membrane at the bottom was permeable to the particles of the smaller diameter d, and impermeable to the particles of the larger diameter D. The process of vertical filtration was accompanied by the simultaneous Brownian motion of the particles and downward movement of the piston. The mixtures with different numerical concentrations of particles, diameter ratio, and initial size of the systems in the vertical direction L_{y} have been studied. The time dependencies of the rejection coefficient k and relative height of suspension h/L_{y} revealed the presence of complete and incomplete separation regimes. The presence of filtration and diffusion-driven stratification of the disks in the vertical direction was observed. The phenomenon of incomplete separation was explained by the formation of an impenetrable barrier from larger particles at the bottom of the deposit.

Impact of polysaccharide and protein interactions on membrane fouling: Particle deposition and layer formation

Membrane fouling, which limits the application of membrane bioreactors, has received considerable research attention in recent years. In this work, filtration modeling was performed in combination with surface plasmon resonance (SPR) analysis to investigate the membrane fouling mechanism. Sodium alginate (SA) and bovine serum albumin (BSA) were used to perform dead-end filtration on hydrophilic and hydrophobic poly (vinylidene fluoride) (PVDF) membranes. The initial foulant deposition and layer formation on membranes as well as the interaction between the BSA and SA were comprehensively analyzed. Results indicated that during SA filtration, initial fouling on hydrophilic membranes were primarily attributed to the particle-membrane interactions, while the fouling on the hydrophobic membrane were dominantly caused by the interactions among SA particles. The interaction between BSA and SA led to more severe membrane fouling and hydrophobic membrane was more sensitive to it, especially in the initial filtration process. The SPR results helped clarify the in-situ deposition behavior of BSA and SA particles on the PVDF surface. Compared to SA, BSA adsorbed faster on the PVDF membrane, and specific interactions played an essential role in BSA adsorption, whereas the deposition of SA on PVDF could be easily removed by shear force. Interactions between BSA and SA could alleviate the bonding between BSA and the PVDF membrane.

Fabrication of Polyamide-6 Membranes—The Effect of Gelation Time towards Their Morphological, Physical, and Transport Properties

Porous polyamide-6 membranes were fabricated via a non-solvent induced phase inversion method, and the influence of gelation time on the properties of the membranes was investigated. Membrane samples with various gelation times were prepared. The evaluation of the membranes’ properties was carried out by various analyses and tests, such as scanning electron microscopy, atomic force microscopy, contact angle, wet and dry thickness, mean pore size measurements, porosity, water uptake, mechanical resistance, hydrodynamic water fluxes, membrane hydrodynamic permeability, and retention testing. The scanning electron microscopy images (both surface and cross-section) demonstrated that the increase in gelation time from 0 (M₀) to 10 (M₁₀) min led to the morphological change of membranes from isotropic (M₀) to anisotropic (M₁₀). The wet and dry thickness of the membranes showed a downward tendency with increasing gelation time. The M₀ membrane exhibited the lowest bubble contact angle of 60 ± 4° and the lowest average surface roughness of 124 ± 22 nm. The highest values of mean pore size and porosity were observed for the M₀ sample (0.710 ± 0.06 µm and 72 ± 2%, respectively), whereas the M₁₀ membrane demonstrated the highest tensile strength of 4.1 MPa. The membrane water uptake was diminished from 62 to 39% by increasing the gelation time from 0 to 10 min. The M₀ membrane also showed the highest hydrodynamic water flux among the prepared membranes, equal to 28.6 L m⁻² h⁻¹ (at Δp = 2 bar).

Ceramic Microfiltration Membranes in Wastewater Treatment: Filtration Behavior, Fouling and Prevention

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganisms and heavy metals mainly contribute to fouling, a complex multifactorial phenomenon. Several strategies, such as chemical cleaning protocols, turbulence promoters and backwashing with air or liquids are currently used in the industry, mainly focusing around early prevention and treatment, so that the separation efficiency of MF membranes will not decrease over time. Other strategies include combining coagulation with either inorganic or organic coagulants, with membrane treatment which can potentially enhance pollutants retention and reduce membrane fouling.